Deleting while iterating over a collection

[dumbledore]

Hi,

using JBoss-4.0.2 with applied Patch (Principal-Propagation-Probems, @see Announcements), this doesn't work correctly, since it only deletes one of two players:

 java.util.Iterator iterator = game.getPlayers().iterator();
 while (iterator.hasNext()) {
 player = (PlayerLocal) iterator.next();
 logger.debug("removing player with namePK="+player.getNamePK());
 iterator.remove();
 }

But this works:

 Object[] playerArray = game.getPlayers().toArray();
 for (int index=0; index<playerArray.length; index++) {
 player = (PlayerLocal) playerArray[index];
 logger.debug("removing player with namePK="+player.getNamePK());
 player.remove();
 }

I think the code with the iterator should work, no?

[fbiaggi]

Hi,
NO, you are removing an instance of the Iterator...

[dumbledore]

Thanks for the reply.

Okay, so this iterator doesn't behave as described in the java-api-docs? The iterator is of the type java.util.Iterator.

Where can I learn more about this topic?

Regards
D.

[schmidts]

"Dumbledore" wrote:
Thanks for the reply.

Okay, so this iterator doesn't behave as described in the java-api-docs? The iterator is of the type java.util.Iterator.

Where can I learn more about this topic?

EJB spec, section 10.3.6 gives more details.

BTW, there's a subtle yet big difference between your two code examples:
first example: removes all players from the "players" collection belonging to the given "game". the player objects still continue to exist.
second example: physically removes all player objects belonging to the given "game". thus automatically removing them from the collection, too.

(sorry, no idea why the first example doesn't work)

[dumbledore]

Thanks, that's it! Removing an object from the iterated collection means deleting the relation, but not the related object.

Regards,
D.